1. Field of the Invention
The present invention concerns a temperature maintenance and metallurgical treatment furnace for a metal in liquid state.
2. Description of Prior Art
The problem of storing and maintenance of the temperature of a liquid metal arises in many metallurgical plants and, nearly systematically, in foundries of medium importance.
It has been proposed to use for this purpose mixers in the form of ladles lined with refractories and provided with an air-combustible burner to store the liquid metal at its outlet from the smelting apparatus and try to limit the decrease of temperature before its later use. Because of their very limited efficiency, nearly all apparatuses have been replaced by induction furnaces, of the hearth type for medium capacities, with channels for the most important ones, but in the smelting of cast iron, the investment and operation costs of the induction furnaces are very substantial.
In steel metallurgy, this problem was resolved by developing a ladle furnace heated with an electric arc.
Two variants utilizing oxygen as fuel have however been tried:
According to one of these variants, an operation of aluminothermy is directly carried out in the ladle and it consists of an addition of aluminum to the metal, then an injection of oxygen followed by a stirring for homogenizing and decanting the liquid metal by means of argon. This process, although used on an industrial basis, enables to heating up the metal, but does not permit any metallurgical treatment.
According to another variant, a maintenance furnace has been produced in the form of the traditional metallurgical ladle, which has been provided with an oxycombustible burner, mounted across a ladle cover, and a bottom porous plug, all in a manner to permit a good heat transfer. This design is however extremely rudimentary, and it leads to important heat losses and also does not permit the use of metallurgical treatments.